package blueBridgeCup;

public class demo1 {

        public static void main(String[] args) {
            long sum = 0;
            long f = 1;
            int mod = 1000000000;
            for (long i = 1; i <= 202320232023L; i++) {
                f = (f * i) % mod;
                sum = (sum + f) % mod;
            }
            System.out.println(sum);
        }
}
